The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Remote access appliances are used frequently in modern day data centers to interface with and establish communications links with a plurality of servers or other serial or Ethernet type devices. Traditionally this has required separate remote access appliances, one for Ethernet and one for serial. In one implementation, the assignee of the present application, Avocent Corp., may also use the Ethernet interface on the remote access appliance to receive digitized data from a digital rack interface pod (DRIP), where the DRIP is interfaced between the server and the remote access appliance. The DRIP receives analog video signals and serial data from the server and converts this information to a digital format, and then forwards the digital information in Ethernet protocol format to the appliance.
A first method by which the DRIP may be powered is through a step down transformer that is plugged into an AC outlet in the data center. To enable this, the DRIP incorporates a power input port to receive the rectified DC voltage from the step down transformer. Obviously, the drawback with this requirement is the need for an external step down transformer and the need for an available AC power outlet to plug the step down transformer into. As one will appreciate, this configuration can also lead to a significant increase in the amount of wiring present in a data center room. Typically a separate DRIP is used to interface a single output port of a remote access appliance to a single server. So if 40 servers are being used in the data center, then 40 DRIPs will be required. If 500 servers are being used, then 500 DRIPs will be required, and so forth. As one can see, the requirement of an available power outlet and the use of a separate power transformer for each DRIP can potentially lead to significant additional costs in implementing a DRIP.
A second means by which a DRIP may be powered is from its server's universal serial bus (USB) port. This approach is typically preferred by many data center managers as it eliminates the use of step down transformers and the need for available AC power outlets to plug the step down transformers into, and thus also makes for a “cleaner” installation with less wiring in the vicinity of the servers. However, if the server shuts down for any reason, then the DRIP will lose its power. This will end any Ethernet session that the DRIP was handling. If the server is then powered back up a short time later, many server models will delay applying power to the designated power pins of its USB port for at least several seconds while it begins to re-boot. So if the DRIP has been relying on power from the server's USB port, this means that the DRIP will have lost power when the server shuts down, and further that power will typically not be applied to the DRIP when the server begins to re-boot. At some point during the boot-up process the server will again begin applying power to the appropriate pins of its USB port, which will then power up the DRIP again, allowing a remote user to establish a new session with the DRIP and the server.
In the event the server has gone down because of a problem, and a data center person needs to troubleshoot the server, the reliance on power from the server's USB port is particularly disadvantageous to the DRIP. This is because when the server begins to re-boot, the BIOS screen, which typically is generated during the first few seconds of the boot-up process, will not be captured by the DRIP because the DRIP will not yet be powered back on. As those skilled in the art will appreciate, the ability to capture the BIOS screen on a server when it re-boots is a significant advantage when it comes to remotely attempting to troubleshoot a problem with a server. Without being able to capture the BIOS screen information, the ability to perform remote access troubleshooting on the server is significantly compromised.
Still further, if the DRIP is not able to draw on power from a step down transformer, but some other power source was able to supply power to the DRIP besides the USB port of the server, then a challenge arises as to how to control which power source the DRIP is to use, and under what condition(s). If the DRIP could intelligently switch to a backup power source (i.e., other than power from a step down transformer) when its primary power source (i.e., power from the USB port of the server) is lost, this would allow the DRIP to remain powered on when the server it is communicating with shuts down. This would also allow the Ethernet session that was in progress with the DRIP to be maintained. This would be extremely valuable because it would allow the DRIP to remain powered on while the server is powered back on and begins to re-boot. In this circumstance the DRIP would be able to capture the BIOS screen information output from the server's USB port.